Technical Field
The present disclosure relates to a display device, and more particularly, to an electroluminescent display device and a method of manufacturing the same.
Description of the Related Art
Electroluminescent display devices are devices which have a structure where a light emitting layer is provided between two electrodes, and thus, emit light with an electric field between the two electrodes to display an image.
The light emitting layer may be formed of an organic material which emits light when an exciton generated by a combination of an electron and a hole is shifted from an excited state to a ground state. Alternatively, the light emitting layer may be formed of an inorganic material such as a quantum dot.
Hereinafter, a related art electroluminescent display device will be described with reference to FIG. 1.
FIG. 1 is a schematic cross-sectional view of a related art soluble electroluminescent display device.
As seen in FIG. 1, in the related art soluble electroluminescent display device, a planarization layer 1, an anode electrode 2, a first bank 3, a second bank 4, a light emitting layer 5, and a cathode electrode 6 are sequentially provided on a substrate (not shown).
The planarization layer 1 planarizes a thin film transistor (TFT) layer (not shown) provided on the substrate, and the anode electrode 2 is provided on the planarization layer 1.
The first bank 3 and the second bank 4 are provided on the anode electrode 2 to define a pixel area. The first bank 3 and the second bank 4 are provided on each of one side and the other side of the anode electrode 2 to expose an upper surface of the anode electrode 2. The first bank 3 is formed of an inorganic material.
The light emitting layer 5 is provided in the pixel area defined by the first bank 3 and the second bank 4, and the cathode electrode 6 is provided on the light emitting layer 5.
In detail, in the soluble electroluminescent display device, in order to increase the convenience and efficiency of a manufacturing process, a light emitting material having a soluble characteristic is sprayed or dropped on the pixel area defined by the first and second banks 3 and 4 through an inkjet printing process, and then, by curing the light emitting material, the light emitting layer 5 is formed.
Particularly, in the related art soluble electroluminescent display device, as described above, the bank is formed of a multilayer including the first bank 3 and the second bank 4 so as to prevent a pileup phenomenon.
The pileup phenomenon denotes that in a case of spraying a light emitting material through an inkjet printing process, the light emitting layer 5 is formed thicker in an edge adjacent to the bank than a center between banks spaced apart from each other. When the light emitting layer 5 is not planarly formed, luminance non-uniformity occurs in a pixel area. For this reason, in the related art, in order to prevent the pileup phenomenon, the bank is formed of a multilayer, and by spraying the light emitting material on an upper surface of the first bank 3, the light emitting layer 5 is planarly formed on an upper surface of the anode electrode 2.
However, the related art soluble electroluminescent display device has the following problem.
As described above, the first bank 3 including an inorganic material should be deposited through a chemical vapor deposition (CVD) process after the planarization layer and the TFT layer are formed, but since the first bank 3 should be patterned through a dry etching or wet etching process in a process of forming the first bank 3 through the CVD process, the anode electrode 2 is damaged in an etching process.